A major threat to treatment efficacy is the dilution of treatment strength through early drop out, sporadic attendance, and marginal participation. This problem represents a significant public health concern given the high rates of attrition and sporadic attendance in child clinic settings. As a result, children and adolescents who do not receive adequate exposure to active treatment components are unlikely to benefit from empirically supported treatments. We propose that the therapeutic alliance and therapist behaviors that facilitate alliance formation are critical for reducing drop out, promoting regular attendance, and maximizing active participation in sessions. Thus, empirically supported treatments should be complemented with empirically based engagement interventions that contribute to alliance formation, and to evaluate the contribution of engagement interventions and alliance to treatment completion, regular attendance, active participation, and treatment outcome in an open trial of CBT for adolescent depression. The proposal involves two studies. The first involves the development and evaluation of observational measures of therapist engagement interventions, therapy alliance, and treatment participation from audio recordings of completed, controlled trial of CBT for depressed and suicidal adolescents. The second study involves the evaluation of associations among engagement interventions, alliance, participation, treatment continuation/attendance, and outcome in an open trial of an empirically supported treatment, cognitive-behavioral therapy, for adolescent depression. An explicit mediational model of therapy process will be evaluated. The identification of effective engagement interventions into manualized treatments for adolescent depression, specifically, and potentially into manuals for a range of adolescent disorders. It is expected that empirically based guidelines for treatment engagement will be essential for the transportation of empirically supported treatments from research to clinical settings.